Rotary regenerator matrix seal with tensioning means



Feb. 13, 1968 A. N. ADDIE ETAL 3,368,613

ROTARY REGENERATOR MATRIX SEAL WITH TENSIONINGMEANS Filed June 12, 1967 2 Sheets-Sheet 1 c INVEN'TORS Feb. 13, 1968 A. N. ADDIE ETAL 3,368,613

ROTARY REGENERATOR MATRIX SEAL WITH TENSIONING MEANS 2 Sheets-Sheet 2 Filed June 12, 1967 //l a; W

United States Patent 3,368,613 ROTARY REGENERATOR MATRIX SEAL WITH TENSIONIING MEANS Albert N. Addie, La Grange Park, and Jack P. Hart, Hinsdale, Ill., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Continuation-impart of application Ser. No. 484,219, Sept. 1, 1965. This application June 12, 1967, Ser. No. 653,288

13 Claims. (Cl. 165-9) ABSTRACT OF THE DISCLOSURE A labyrinth sealing arrangement in a rotary regenerator matrix of the drum type. The matrix has rims which are spaced by stitieners. Labyrinth sealing strips at the outer, cold side and inner hot side are mounted in structure which prevents any pressure loading against them by the heat transfer pack. The cold side sealing strips are held in tension between the two rims, and the hot side strips are segmented and are connected to the cold side strips so as to be aligned by the cold side strips. This tension tends to keep the cold side strips and, therefore, the hot side strips straight, and allows them to remain substantially straight notwithstanding thermal distortion of the heat transfer pack and the tendency of the sealing to distort because of temperature gradients. A cold side strip of high heat conductivity may further reduce distortion.

This application is a continuation-in-part of our application Ser. No. 484,219 for Regenerator Matrix filed Sept. 1, 1965, now abandoned.

This invention relates to heat exchangers and more particularly to rotary regenerator matrices for transferring heat from one fluid to another. These matrices are particularly useful with gas turbine engines. Gas turbine engines including regenerators are disclosed in US. Patents No. 3,116,605 to Amann et al. and No. 3,077,074 to Collman et al.

Regenerator matrices are subject to a wide divergence of fluid temperatures and this condition gives rise to sealing problems as the surfaces of the matrices distort.

An object of the present invention is to provide a regenerator matrix, preferably of the radial flow type, having improved seals at the inside and outside faces of the matrix, which seals remain substantially stable in form to gain effectiveness in sealing despite the application of heat at widely divergent temperatures and at localized portions of the matrix.

The invention is thus dircted to the same problem as the regenerator structure of the U8. patent application of Wall, Ser. No. 425,789, filed Ian. 15, 1965, for Matrix Seal, assigned to the owner of this application. The present invention may in part be considered as a further development of or improvement of the Wall matrix.

A feature of the present invention is a matrix in the form of an annulus including rims joined by spaced labyrinth seal assemblies of stable sealing edge formation, the rims serving to retain a cylindrical series of heat transfer packs which are movable independent of the radial seal assemblies.

This and other important features of the invention will 3,368,613 Patented Feb. 13, 1968 now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

FIGURE 1 is a perspective view of a matrix presented as one embodiment of the present invention;

FIGURE 2 is an enlarged outside view of an end portion of the matrix looking in the direction of the arrows 22 of FIGURE 1;

FIGURE 3 is an enlarged sectional view through one side of the matrix and looking in the direction of the arrows 3-3 in FIGURE 1 with portions broken away better to illustrate the construction;

FIGURE 4 is an enlarged sectional view looking in the direction of the arrows 44 in FIGURE 2;

FIGURE 5 is an exploded and perspective view of portions of parts constituting a radial seal assembly of the type shown in FIGURES 2, 3, and 4;

FIGURE 6 is a view similar to that of FIGURE 3 but showing a modified version; and

FIGURE 7 is a part sectional, perspective and partially exploded view of the radial seal arrangement shown in FIGURE 6.

The matrix of FIG. 1 is an annular body having a rim at each end, the rims being made up of end rings 10 and 12 and retaining rings 14 and 16 which are fixed to the end rings, respectively. It includes a series of outer sealing strips 18, a series of inner sealing strips 20, and a series of seal spacer plates 22 and 24, all these series extending from the ring 10 to the ring 12. The rims are located With respect to each other by twenty-five stilfeners 26 extending between the rims and provided with tongues 28 and 30 received in annular grooves 32 and 34 of the rings 10 and 12 respectively. Referring to FIG. 2, it will be apparent that the stitfeners are much heavier than the sealing strips and spacer plates, and that the sets of sealing strips and spacer plates are much more numerous than the stiifeners. Shim pack-s 36 made of stainless steel fill the spaces between adjacent sets of spacer plates 22 and 24.

The nature of these packs 36 is immaterial insofar as the present invention is concerned and is subject to variation but it will be understood that each pack defines radial pas-sages through which the gases or fluids may flow to effect the heat exchange. The grooves 32 and 34 are also employed in retaining the shim packs.

The sealing strips 18 and 20 project radially outward and inward slightly beyond the shim packs and spacer plates and are disposed to cooperate, in the nature of labyrinth seals, with fixed seal bars disposed in the regenerator so as to provide a seal between high and low pressure zones in the regenerator.

The sealing strips 18 are held under tension by providing each end of the sealing strip with a transverse pin 38 to bear against registering cam'su-rfaces 40 of slots 42 formed in the rings 10 and 12. The tension in each outer sealing strip tends to hold it straight, acting to counteract any bending moment due to a thermal gradient existing in the sealing strip. This effect tends to be self-compensating, since the larger the amount of bowing of the sealing strip the greater is the restoring moment set up by the tension on the strip.

Each stiffener 26 is fixed to each ring 10 or 12 by two bolts 44 and also by a bolt 46, which latter also serve to attach theretaining ring 14 or 16. Each retaining ring 3 includes a lip 50 which overlies the end of sealing strip 18 to retain the pin 38 in the slot 42.

The stiifeners 26 hold the rims apart, and the sealing strips are of such length between the pins 38 that they are held in tension at all times. The tension will vary with differences in the rate of heating of the thin sealing strips and the thick stiifeners during transients in operating temperature levels. If there is a difference in coefficients of thermal expansion between members 18 and 26, this also will cause some variation in tension with temperature level in steady state operation. It is contemplated that the strips 18 be always under some tension to provide a force tending to hold them straight.

Some experience has been had with sealing strips 18 made of beryllium copper, the reason for selecting this material being its high thermal conductivity which would tend to reduce the bowing effect, as there would be less temperature difference between the inner and outer edges of the strip. However, in the particular installation in which the beryllium copper was tried, it was not particularly successful, having less endurance than was desired. It is now preferred to use a high-temperature stainless steel similar to that of the remainder of the matrix, or other high-temperature resistant alloy. However, a copper alloy or other highly conductive material may be desirable in some installations.

It was contemplated that the copper alloy be used only on the outer or cold side of the matrix, since the hot side in the gas turbine application is entirely too hot for such materials. The inner sealing strips 20 are assembled to, and their distortion is controlled by, the outer sealing. strips 18. Each outer sealing strip has radial spacer slots 52, each of which receives a slotted tongue 56 of a spacer portion of the inner sealing strip 20 to complete a snap fastener connection between the strip 18 and the strip 20. Each inner sealing strip 20 must be capable of withstanding high temperatures such as 1450" F., and a suitable material for the strip is 73% nickel and 15% chromium alloy. Each strip 20 is segmented by slots 60 permitting relatively unrestrictive lengthwise expansion of the plate while the segmented edge is held substantially straight by the struts 56 connecting strips 18 and 20'.

When the strips 18 and 20 are coupled together they define rectangular apertures 62 which are larger than the rectangular bosses 64 and 66 of the spacer plates 22 and 24 respectively (FIG. The bosses 64 and 66 meet within the apertures 62 and bear the circumferential pressure of the heat transfer material; thus, the sealing means including strips 18 and 20 and struts 56 are free to move and are not bound by the circumferential pressure which otherwise would be exerted against them by the heat transfer material. As shown clearly in FIG. 4, the spacer plates 24 and 26 are tapered radially.

The separable connection of the strips 18 and 20, in addition to making possible the use of diverse materials, also makes it possible to replace the sealing strips without disassembling the matrix.

When the matrix is in operation, the inner hot side expands more than the outer cooler side, and therefore the matrix distorts so as to be slightly spool-shaped. The clearance between the sealing means and the spacer plates is such that the sealing means may remain straight although the spacer plates distort with the rest of the matrix. The cold side strips are held in tension and are substantially rectilinear. They locate through the struts a number of points on the inner sealing strips. These points are thus held substantially in a straight line. The inner side sealing strips may bow to some extent, but since the bowing is individual to each short segment the total excursion or variation in the seal gap is slight.

However, there is one effect not hitherto mentioned which tends to cause distortion of the outer side sealing strips. When the matrix distorts, the rims cone slightly, converging toward their outer edges. This inclination, acting upon the pins 38, puts a slight bending load on the sealing strips. Put another way, the point of application of the tension on the strips moves slightly away from the center of the strips, creating a slight curvature of the edge of the strips. This effect is considerably less pronounced when the sealing structure of the second embodiment of the invention, shown in FIGS. 6 and 7, is adopted.

Referring to FIGS. 6 and 7, the second form of the invention tends to eliminate the disadvantage referred to in the preceding paragraph, and has other advantages. In this form the matrix rims include end rings 70 and 72 having facing grooves 74 and 76, respectively. Spacer plates 78 and 80 have facing and contacting rectangular bosses 82 and 84, respectively. These plates are similar to those shown in FIG. 5 but have tongues 86 received in grooves 74 and 76 of the end rings. A stainless steel sealing plate 88 defines the outer sealing strip 89 joined by integral struts 91 to the inner side sealing strip 93. The strips 89 and 93 and struts 91 define apertures 90, each of which freely receives a mating pair of bosses 82 and 84.

Stiffeners 92 (FIG. 6), corresponding to stiffeners 26 of the first embodiment, are rigidly fixed to the rings 70 and 72 by long cap screws, some of which are indicated at 94. Two such screws are provided at each end of the 'stiffeners. The side of the end rings adjacent the heat transfer material is recessed from the outer surface, as indicated at 96 and 98. As shown in FIG. 7, the stiifeners extend into the recesses 96 and 93.

Also located in recesses '96 and 98 are outer retainer segments 100 and 104 and inner retainer segments 102 and 106, which extend through the are from one stiffener plate to the next, traversing the packs of the heat transfer material and the sealing structures. These segments are recessed to retain a spring support in the form of an 'arcuate I-beam section strip 112 or 114 which has an outer flange 116 or 118. The segments 100 and 104 are retained by cap screws 120 and 122 which extend through them and are threaded into the segments 102 and 106, retaining these also in abutment with the segments 100 and 102. The inner flange of each I-beam strip 114, 116 and the adjacent parts of the retainer segments are slotted as indicated at 124 (FIG. 7) at each seal plate 88 to receive a tab 126 extending from the outer sealing strip 89, which tab has a rectangular hole 128. Keys and 132, which are curved rectangular strips, are inserted through the holes 128 back of the inner flange of the I- beam strip. Tension is applied to the strip 89 when the segments 100, 102, 104 and 106 are bolted to the end rings 70 and 72. The amount of the tension may be adusted by selecting keys 130 and 132 of suitable Width and by applying suitable shims between plates 100 and 104 and the end rings. Thus the tension in the sealing strip 89 causes each seal plate 88 to remain nearly straight notwithstanding the thermal gradients in the matrix. The

web portion of the I-beam strip can deflect radially of the matrix structure to allow the sealing strip 89 to remain straight notwithstanding deformation of the rim, thus eliminating the disturbing effects between pins 38 and the rims in the form of FIGS. 2 to 5. The inner sealing strip 93 is cut through as indicated at between the struts 91 so that the hot side may expand more than the cold side. Distortion of the individual short segments of the sealing strip 93 is not significant. These segments may have overlapped ends, but this is not necessary or preferred.

With the arrangement of FIGS. 6 and 7, the heat transfor and sealing structures between any two adjacent stiffeners may be assembled and installed in, or removed from the matrix drum without disconnecting the end rings from the stiffeners. With the rings 100, 102, 104 and 106 removed, the segmental pack may be installed in place and then secured by installing these retainer segments.

In both forms of our invention of this application the cold side seal contour is established by the tension exerted on the cold side sealing strips by the matrix frame consisting of the stiffeners and rims. The position of the hot side sealing strips is determined by the cold side sealing strips. Both of these are features of significance. Clearly it would be possible to apply tension independently to hot and cold side seal strips in some cases, but in a high temperature regenerator it is not feasible to put sufiicient tension on the hot side seal strips to maintain them straight.

FIG. 7 illustrates three small hard metal contact pieces 136 fixed to the strip 89 at the center of the span of the latter. These pieces may provide a positive location radially of the matrix for the center of strip 89 by cooperation with a guide on a seal bar with which it coacts, the sealing strip thus being located at both ends and in the middle for more accurate control of the preferably quite close spacing between the sealing strip and the fixed seal bar with which it cooperates. This concept is more fully disclosed and is claimed in our copending application Ser. No. 645,174, filed June 12, 1967, which is a continuationin-part of our above-mentioned application Ser. No. 484,219.

Reference to the tension in the cold side sealing strips tending to maintain them straight should not be interpreted restrictively. To cold and hot side sealing strips may define a sealing edge which is intentionally non-rectilinear when the sealing strip is cold. The tension in the strip will tend to retain the desired edge contour notwithstanding thermal effects. In other words, tension acts to hold the strip straight, whether or not the edge is straight when the strip is straight.

While the present invention is disclosed in a radial-flow matrix, it is applicable to axial-flow matrices.

The detailed description of preferred embodiments of our invention for the purpose of explaining the principles thereof is not to be considered :as restricting the invention, since many modifications may be made by the exercise of skill in the art within the scope of the invention.

We claim: 1. A rotary regenerator matrix comprising, in combination,

two spaced coaxial rims, stiifeners structurally connecting and spacing the rims, foraminous heat transfer structure having two faces and extending from one rim to the other open to flow of fluid through the space between the rims from face to face of the heat transfer structure,

labyrinth sealing strips extending across a face of the heat transfer structure from rim to rim and extending outward from the face of the heat transfer structure adapted to cooperate with sealing means disposed adjacent the matrix,

means within the heat transfer structure providing clearance for the labyrinth sealing strips from the heat transfer structure so that the labyrinth sealing strips are unafiected by distortion of the matrix,

and means coupling the ends of each said sealing strip directly to the rims, the coupling means being adapted to subject the strips to tension exerted by the rims, the relative dimensions of the parts being such that the sealing strips are held in tension resisted by compression of the stifieners transmitted from the strips to the stiffeners by the rim.

2. A matrix as defined in claim 1 in which the coupling means comprises a shoulder on each rim and a transverse pin at each end of the sealing strip lodged against the shoulder.

3. A matrix as defined in claim 1 in which the coupling means embodies a tension member adapted to flex in the face-to-face direction.

4. A matrix as defined in claim 3 in which the tension member is an I-beam the web of which is adapted to flex,

in which one flange of the I-beam is slotted to receive the ends of the sealing strips and the other flange is attached to the rim,

the ends of the sealing strips have holes therein, and

keys are disposed through the holes bearing against the sealing strips and the said one flange.

5. A matrix as defined in claim 1 in which the coupling means includes a swingable connection such as to permit a change in the angle between the sealing strip and the rim.

6. A rotary regenerator matrix comprising, in combination,

two spaced coaxial rims,

stitfeners structurally connecting and spacing the rims,

foraminous heat transfer structure having two faces and extending from 'one rim to the other open to flow of fluid through the space between the rims from face to face of the heat transfer structure,

labyrinth seal means extending across the heat transfer structure from rim to rim and extending outward from the faces of the heat transfer structure adapted to cooperate with sealing means disposed adjacent the matrix,

spacer means within the heat transfer structure providing clearance for the labyrinth seal means from the heat transfer structure so that the labyrinth seal means are unaffected by distortion of the matrix;

each seal means comprising a first sealing strip extending across one face of the matrix,

a second sealing strip extending across the other face of the matrix,

and strut means distributed along the span of the said strips interconnecting the first and second strips so as to maintain a constant distance beween the strips at the strut means;

and the matrix including means adapted to put the first sealing strips in tension so as to bias the sealing strips toward stable edge contours lengthwise of the strips.

7. A matrix as recited in claim 6 in which the last recited means is means coupling the ends of said first sealing strips directly to the rims, the coupling means being adapted to subject the said first sealing strips to tension exerted by the rims, the relative dimensions of the parts being such that the said first sealing strips are held in tension resisted by compression of the stiifeners transmitted by the rims from the strips to the stitfeners.

8. A matrix as recited in claim 6 in which the second sealing strip is divided into segments connected to the first sealing strip by the strut means.

9. A matrix as recited in claim 8 in which the struts are bifurcated and each said segment connects to two struts.

10. A matrix as recited in claim 8 in which the segments terminate between the struts and each said segment connects to one strut.

11. A matrix as recited in claim 6 in which each seal means is a unitary structure.

12. A matrix as recited in claim 6 including separable connecting means joining the first and second sealing strips.

13. A rotary regenerator matrix having an annular body of generally rectangular cross-section with two faces and two sides comprising, in combination,

coaxial rims at the sides of the matrix,

a number of stifleners extending from rim to rim distributed around the circumference of the rim, the stiifeners connecting the rims together and being adapted to resist compressive loads,

and heat transfer material disposed between the stiffeners, the heat transfer material having a porous structure providing for fluid flow from one face to the other, the matrix normally having a temperature gradient between the faces when in operation,

labyrinth sealing means including sealing strips extending across the faces from rim to rim and projecting slightly from the faces for cooperation with structure external to the matrix, the sealing strips 7 8 extending from rim to rim of the matrix, at least References Cited some of said sealing strips being fixed directly to UNITED STATES PATENTS said rims and being of such length as to be marntained in tensicn by said rims so as to be biased 11811603 5/1965 Bubmak at toward a stable edge contour by such tension, 5 3186479 6/1965 Mondt 165 10 3,216,487 11/1965 Gallagher l65-9 and spacer means disposed Within the matrix engaging the heat transfer material and taking circumferential pressure of the heat transfer material ofi the sealing ROBERT Pnmary Exammer' means. A. W. DAVIS, Assistant Examiner. 

